The invention relates to new chemical compounds useful as perfumes or as components of perfumes. More specifically it relates to alkyl-substituted 2-acylindenes and isomeric mixtures thereof.
There is a continuing search for materials having useful perfumery fragrance characteristics. These materials are sought either as replacements for naturally occurring compounds or as totally new scents or odour notes in their own right. For practicability reasons such materials should possess other favorable properties e.g. substantivity and stability in applications, all in addition to their useful odour notes.
It is the object of the present invention to provide a series of novel and practicable synthetic materials or isomeric mixtures thereof, being alkyl-substituted indenes comprising an acyl moiety in the 2-position, and possessing very useful and strong odours with woody, straw- and hay-like notes. These novel indenes are represented by the generic Formula I 
wherein R1, R2 each represent a lower alkyl group and R3, R4, R5, R6, R7 and R8 each represent hydrogen or a lower alkyl group or wherein two substituents chosen from R1, R2, R3, R4, R5, R6, R7 or R8 together may represent a di-, tri- or tetra- or pentamethylene moiety or a lower alkyl-substituted di-, tri- or tetra- or pentamethylene moiety and the remaining substituents represent hydrogen or a lower alkyl group, and wherein the total number of carbon atoms in formula I is twenty two or less, with the proviso that R1 and R2 together do not represent a tetramethylene moiety if R3, R4, R5, R6, R7 and R8 all represent hydrogen, and with the proviso that R8 does not represent hydrogen if R1, R2, R4, R5, R6, R7 and R8 all represent a methyl group.
In the present context the term xe2x80x9clower alkylxe2x80x9d indicates a straight or branched alkyl group or a cycloalkyl or alkyl-substituted cycloalkyl group, an of 1-6 carbon atoms.
It will be apparent that the novel indenes can exist in a variety of positional, stereoisomeric and enantiomeric forms and it is intended that these be included within the structural formulae.
In the compounds of the invention represented by the generic Formula I. R1, R2 each represent a lower alkyl group and R3, R4, R5, R6, R7 and R8 each represent hydrogen or a lower alkyl group, or two substituents chosen from R1, R2, R3, R4, R5, R6, R7 or R8 together may represent a di-, tri- or tetra- or pentamethylene moiety or a lower alkyl-substituted di-, tri- or tetra- or pentamethylene moiety and the remaining substituents represent hydrogen or a lower alkyl group, with the proviso that R1 and R2 together do not represent a tetramethylene moiety if R3, R4, R5, R6, R7 and R8 all represent hydrogen, and with the proviso that R3 does not represent hydrogen if R1, R2, R4, R5, R6, R7 and R8 all represent a methyl group.
In a preferred embodiment of the invention R3 represents an alkyl group of four carbon atoms or less. In a more preferred embodiment R8 is a methyl group. In an alternative embodiment R1, R2 are selected from methyl and ethyl groups and R4, R5, R6, R7 and R8 each are selected from hydrogen, methyl and ethyl groups with a total number of carbon atoms in R1, R2, R3, R4, R5, R6, R7 and R8 together of eight or less. According to a specially preferred embodiment R1, R2 and R4 represent each a methyl group.
The compounds of the invention are new. Only a few, simple alkyl-substituted 2-acylindenes are known, see for example Chem. Abstr. 114:121685; 105:115070; 93:238411; 107:175558; 90:54197; 84:121530; 83:131170; 117:131346; 110:94192; 109:54897; 107:217199; 107:40061; 105:226283; 95:23687; 79:136870 and 79:115338. These compounds appear to be mainly of scientific interest or are useful as intermediates for veterinary sedative antagonists or are rated odorless. None of them relates to possible uses as perfume or as component of perfumes.
In British patent application 2233645 the preparation and the use for the improvement of the fragrance of perfume compositions of 2-acylindanes are disclosed. Although these indanes are said to have no particularly powerful fragrance themselves, they would have an extra xe2x80x9charmonizingxe2x80x9d and xe2x80x9crounding offxe2x80x9d effect when added to other odoriferous materials in very low concentrations. The method of preparation of the disclosed indanes is mainly of academic interest and involves many laborious and impractical steps with low overall yields and would not be suitable for cost-effective industrial production.
For the chemist skilled in the art it will be apparent that the structural and three-dimensional conformation of the novel 2-acylindenes of the present invention differs significantly from the 2-acylindanes disclosed in British patent application 2233645. For the fragrance chemist skilled in the art it is understood that the three-dimensional position of the osmopheric group, being the ketone moiety of the acyl group, relative to the plain of the backbone of the molecule is decisive for the odour characteristic of the molecule. In 2-acylindanes the carbon atom in the 2-position is using four sp3-hybridized orbitals to form tetrahedral bonds with the four atoms to which it is connected in a three-dimensional configuration. Consequently the position of the acyl moiety is out of the plain of the cyclic skeleton of the molecule. This is significantly different from the situation in 2-acylindenes of the present invention, wherein the carbon atom in the 2-position uses three sp2-hybridized orbitals to form trigonal bonds with the three atoms to which it is connected, in a two-dimensional configuration. Therefor, in the case 2-acylindenes the position of the acyl moiety is in the plain of the cyclic skeleton of the molecule, which for fragrance chemists skilled in the art makes the odour characteristics unpredictable and unexpected over the prior art.
The novel indenes of the invention can be prepared by methods known to the art for analogous compounds e.g. as described in the literature references herein above. Of the methods known, the preferred method for each compound of the invention may be different and will depend on considerations of economics, availability of starting materials, byproduct formation, technical feasibility, safety, organoleptic grade produced, and the like, which parameters, circumstances and conditions may be subject to change over time, location, facility, etc.
A preferred chemical method in this context involves selective formylation or acylation of the alkene moiety of indenes of the generic Formula II, 
wherein the provisos for R1, R2, R4, R5, R6, R7 and R8 are the same as defined herein above for Formula I, by general methods known to the art e.g. as set forth in J. March, Advanced Organic Chemistry: Reactions, Mechanisms and Structure, 4th edition, J. Wiley and Sons, N.Y., 1992, pp. 598-600, and references cited therein, and in G. A. Olah, Friedel Crafts and Related Reactions, Interscience Publishers, 1964, vol. III, part 2, pp. 1033-1071, and references cited therein. The starting indenes of Formula II can be prepared by methods known to the art e.g. as set forth in the references cited in CA 95:42765; CA 95:24598; CA 93:71383; CA 74:87684; CA 54:24584; CA 47:2169; CA 44:1056 and CA 43:5762.
An alternative preferred chemical method of preparation of the compounds of the invention involves conversion under Friedel Crafts acylation conditions, generally known to the art, e.g. as set forth in the references cited herein above, of indanes represented by the generic Formula III, wherein the provisos for R1, R2, R4, R5, R6, R7 and R8 are the same as defined 
herein above for Formula I, and wherein R9, R10, R11, R12, and R13 each represent hydrogen or a lower alkyl group or wherein two substituents chosen from R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, R12 or R13 or together may represent a di-, tri- or tetra- or pentamethylene moiety or a lower alkyl-substituted di-, tri- or tetra- or pentamethylene moiety and the remaining substituents represent hydrogen or a lower alkyl group, and wherein the total number of carbon atoms in formula III is fifty or less. The indanes of Formula III can be prepared by methods known to the art e.g. as set forth in G. A. Olah, xe2x80x9cFriedel Crafts and Related Reactionsxe2x80x9d, Interscience Publishers, 1964, Vol. II, part 2, pp. 952-962 and the references cited therein
The novel 2-acylindenes of the invention exhibit a variety of useful odour nuances with long-lasting, strong and diffusive, dry woody, straw- and hay-like notes with radiance and odour substantivity, which makes them specially suitable to be applied in fabric care, functional care and personal care consumer products. They bring a significant contribution to woody ambery fragrance combinations and as such add great depth to a fragrance combination even in very small quantities. They can be used as fragrances per se or as components of a fragrance composition. The term xe2x80x9cfragrance compositionxe2x80x9d is used to denote a mixture of compounds including, for example, natural oils, synthetic oils, alcohols, aldehydes, ketone, esters, lactone, ethers, hydrocarbons, nitrites and other classes of chemical compounds which are admixed so that the combined odours of the individual components produce a pleasant or desired fragrance. Such fragrance compositions of the novel compounds of the invention alone can be used in conjunction with carriers, vehicles or solvents containing also as needed, dispersants, emulsifiers, surface-active agents, aerosols propellants, odour release influencing agents and the like. In fragrance compositions the individual components contribute to their particular olfactory characteristics, but the overall effect of the composition is the sum of the effect of each ingredient. Thus, the compounds of the invention can be used to alter, enhance, or reinforce the aroma characteristics of the other natural or synthetic materials making up the fragrance composition, for example, by highlighting or moderating the olfactory reaction contributed by another ingredient or combination of ingredients.
The amount of the compounds of the invention that will be effective, depends on many factors including the characteristics of the other ingredients, their amounts and the effects which are desired. It has been found that as little as 0.001% by weight of compounds of this invention can be used to alter the effect of a fragrance composition. The amount employed will depend on considerations of cost, nature of end product, the effect desired in the finished product, and the particular fragrance sought, but will usually not be more than about 40% by weight.
The compounds disclosed herein can be used in a wide variety of applications, by way of example but not limited thereto, detergents and soaps, fabric softeners, fabric care products, fabric sprays, fabric deodorants, ironing added products, dryer added product, optical whiteners, odour masking products, personal hygiene care products, air fresheners, perfumes, colognes, after shave lotions, preparations such as bath oils and bath salts, hair preparations such as lacquers, brilliantines, pomades and shampoos, cosmetic preparations such as creams, deodorants, hand lotions and sun screens, powders such as talcs, dusting powders, face powders, masking agents, household products such as bleaches, cleaners, dish washing products, scourers, toilet cleaners, carpet cleaners and in technical products such as paints, inks, shoe polish and automobile wax.
The following examples illustrate the invention without limitation thereto.